Hepatitis B (HBV) and Hepatitis C (HCV) are distinct viral infections that primarily target the liver, leading to inflammation and potential damage. These viruses represent a significant global health challenge, affecting hundreds of millions worldwide. Both can cause serious health issues, including severe liver damage and cancer, contributing to an estimated 1.3 million deaths annually.
Understanding HBV and HCV
HBV is a DNA virus, belonging to the Hepadnaviridae family, with a partially double-stranded DNA genome. In contrast, HCV is an RNA virus, classified within the Flaviviridae family, which also includes viruses like West Nile and Zika.
Both viruses primarily infect and replicate within liver cells, leading to various degrees of liver damage. While both can cause acute (short-term) and chronic (long-term) infections, their likelihood of becoming chronic differs. HBV infection can lead to chronic disease in hundreds of millions, while approximately 50 million globally have chronic HCV infection.
How They Spread
The transmission routes for HBV and HCV largely involve exposure to infected blood or bodily fluids. HBV spreads through contact with blood, semen, or other bodily fluids from an infected person. Common ways this occurs include sexual contact, sharing needles or drug injection equipment, and from a pregnant person to their newborn during childbirth. HBV can also be transmitted through unsterile medical or dental equipment, tattooing, body piercing, and sharing personal items like razors or toothbrushes that may have traces of blood.
HCV is primarily transmitted through blood-to-blood contact. The most frequent routes involve sharing needles and syringes among people who inject drugs. Blood transfusions were a significant source of HCV transmission, but this risk has been largely eliminated in many countries. While less common than for HBV, HCV can also be transmitted sexually, with the risk increasing with multiple sexual partners, anal sex, or in individuals with HIV. Mother-to-child transmission of HCV occurs in about 3% to 5% of infants born to infected mothers.
Recognizing Symptoms and Progression
Acute HBV and HCV infections often show no symptoms, especially in young children with HBV. When symptoms do occur for either virus, they can appear anywhere from a few weeks to several months after exposure. Common symptoms include fatigue, nausea, vomiting, abdominal pain, dark urine, and jaundice (yellowing of the skin or eyes). Some people with acute HBV may also experience fever, joint pain, and loss of appetite.
The progression from acute to chronic infection differs significantly between the two viruses. For HBV, about 90% of infected infants and up to 50% of children aged 1-5 years will develop chronic infection. In contrast, about 95% of adults with acute HBV infection recover completely and do not become chronically infected. For HCV, approximately 55% to 85% of individuals with acute infection will develop chronic HCV infection.
Untreated chronic HBV and HCV infections can lead to serious long-term health consequences. Both can cause cirrhosis and liver failure. Chronic HBV is a leading cause of hepatocellular carcinoma, and chronic HCV also increases the risk of liver cancer. These complications can take decades to develop, often silently progressing without noticeable symptoms until significant liver damage has occurred.
Diagnosis and Management
Diagnosis of both HBV and HCV involves blood tests. For HBV, a “Hepatitis B Panel” includes three tests: Hepatitis B surface antigen (HBsAg) for current infection, Hepatitis B surface antibody (anti-HBs) for protection from vaccination or past infection, and Hepatitis B core antibody (anti-HBc) for past exposure. A positive HBsAg for more than six months indicates chronic HBV. For HCV, an antibody test (anti-HCV) determines if a person has ever been exposed. If positive, a nucleic acid test (NAT) for HCV RNA confirms current infection.
Managing HBV and HCV infections involves different approaches. For HBV, a highly effective vaccine is available and recommended for all infants at birth, followed by additional doses. This vaccine prevents liver cancer caused by HBV. For individuals with chronic HBV, antiviral medications like tenofovir or entecavir can suppress viral replication and reduce the risk of cirrhosis and liver cancer, often requiring long-term treatment.
HCV management has advanced with direct-acting antiviral (DAA) medications. These oral medications target specific viral proteins, and combination DAA therapies can cure over 95% of individuals with HCV infection within 8 to 12 weeks. While there is no vaccine for HCV, early detection through screening is important for curative treatment and preventing long-term liver damage. General preventative measures for both viruses include avoiding shared needles, practicing safe sex, and ensuring sterile medical procedures.